Cleanable touch and tap-sensitive surface

ABSTRACT

A touch sensitive surface having touch-capacitive and vibration sensors. This surface allows the user to rest their fingers on the keys and type as they would on a regular keyboard. As the user places their fingers on the keys, the touch capacitive sensors (one per key) report the signal strength level of each key touched to a processor, but no keystroke is issued by the processor until a corresponding “tap” (ie. vibration) is detected. When a tap is detected, the processor references the status of the touch capacitance sensors before, during, and/or immediately after the moment in time the tap occurred.

PRIORITY CLAIM

This application claims the benefit of U.S. Provisional Application Ser.No. 60/973,691 filed Sep. 19, 2007, which is incorporated by reference.

FIELD OF THE INVENTION

The invention relates to a smooth touch-sensitive surface that is easyto clean and that allows the user to rest their hands or fingers on thesurface without causing an event actuation. More specifically, the touchsurface may be used as a computer keyboard for inputting text andcommands.

BACKGROUND OF THE INVENTION

The origin of the modern keyboard as the primary method for inputtingtext and data from a human to a machine dates back to early typewritersin the 19^(th) century. As computers were developed, it was a naturalevolution to adapt the typewriter keyboard to be used as the primarymethod for inputting text and data. While the implementation of the keyson a typewriter and subsequently computer keyboards have evolved frommechanical to electrical and finally to electronic, the size, placement,and mechanical nature of the keys themselves have remained largelyunchanged.

Computers, and their accompanying keyboards, have become pervasive inenvironments across numerous industries, many of which have harshconditions not originally accounted for in the computer and keyboarddesigns. For example, computers are now used in the kitchens ofrestaurants, on production floors of manufacturing facilities, and onoil drilling rigs. These are environments where a traditional keyboardwill not remain operational for very long without cleaning, due toextreme contamination conditions.

Computers are also being used in environments where extreme cleanlinessis required. Hospital nursing stations, operating rooms, examinationrooms, dental treatment rooms, and diagnostic facilities all nowcommonly make use of computers. These are environments where infectioncontrol is extremely important. Keyboards become a particularlydifficult problem to resolve in achieving an antiseptic environmentbecause of the difficulty presented in cleaning them. This is evidencedby a study conducted by the Tripler Army Medical Center in Honolulu, Hi.that found that nearly 25 percent of the keyboards used in the hospitalharbored the type of bacteria that is responsible for 95% of allhospital-acquired illnesses.

Because of the mechanical nature of the keys on traditional keyboards,they contain many moving parts that result in cracks and cavities wheredust and contamination can collect. Further, keyboards are repeatedly incontact with human hands—one of the most common transporters of dirt,bacteria, viruses, and other infectious agents. Cleaning a traditionalmechanical keyboard presents difficult challenges. On a typicalkeyboard, there are over 500 individual surfaces to clean (counting thetops and sides of each key). Many of these surfaces are very difficultto access and clean effectively, especially without pressing down on thekeys, meaning they must be cleaned while the keyboard is disabled or thecomputer turned off.

Some past inventions have sought to address the problem of clean-abilityby using sealed rubber keys on the keyboard. These keyboards are madefrom soft, pliable rubber (typically silicon rubber) that is molded andsealed over the electrical key contacts providing a moisture barrier.This makes it possible, for example, to place the keyboard under runningwater to clean it. The keys still have mechanical travel and a tactilefeel, which is generally considered favorable for fast and efficienttyping.

While this approach makes it possible to clean the keyboard, there arestill many problems related to the use of rubberized keyboards. First ofall, rubber is porous, which means dirt and other contaminants tend tocollect more easily at the microbial level and are more difficult towipe clean, often requiring more rubbing and/or solvents to separate thecontaminants from the rubber. Second, in typical configurations, therubber keys protrude from the rubber base so there are still small gapsbetween the keys that are difficult to get to and clean by wiping.

Some rubber configurations avoid the problem of gaps between keys bystretching a smooth thin sheet of silicon rubber over the entirekeyboard area of a regular keyboard, and then marking the key locationswith a graphical image on the rubber cover. This approach makes itpossible to clean the keyboard by wiping, and still maintains thetactile feel of the travel and click of the mechanical keys below thecover (although it is somewhat dampened by the rubber cover). However,the problem of the porous nature of the rubber still exists. Finally,the rubber membrane is soft and susceptible to cracks, tears, and deepscratches. These can cause further problem areas for potentialcontamination.

Another type of cleanable configuration is a membrane keyboard (orkeypad). These are typically made by sandwiching a sensor membranebetween a hard flat surface (such as plastic) and a top covering madefrom vinyl or Mylar®. These units are completely sealed by the topcovering, permitting them to be cleaned. The sensor membrane istypically made up of two thin sheets with a conductive grid on each thatmake contact with each other when the membrane is pressed firmlytogether. The amount of mechanical travel required to do this is verysmall and virtually imperceptible to the human touch, meaning there isno tactile feedback when a key is pressed. Some membrane keyboards arecompletely smooth and flat, while others have small protrusions in thetop covering to indicate the outlines of each key.

The advantage of a membrane keyboard is that it is flat with no gapsbetween the keys, making it easy to wipe and clean. The primaryshortcoming of a membrane keyboard is that is difficult to type onefficiently. It is often difficult to feel the keys, resulting in theuser having to look at the keyboard. The lack of tactile feedback alsoslows typing. And finally, the amount of force to actuate a membrane keyis usually much higher than that of a normal keyboard, causing the userto fatigue more quickly.

Yet another way to address the clean-ability problem is to cover thekeyboard with a commercially available plastic film that has been moldedto fit over each key. The plastic film is pliable, allowing the user tofeel the movement of each key, so they are still able to type withoutlooking. The cover can be removed, washed, and then put back on thekeyboard. In some instances, users cover their keyboard with stretchyplastic wrap (commercially known as Saran wrap) in order to make it morereadily cleanable.

Because the molded cover has indents for each key, it is still difficultto clean while in place; it is usually necessary to remove the cover inorder to clean it. The molded plastic film also impedes the movement andfeel of the keys making it somewhat more difficult to type when it is inplace.

To overcome the problem of clean-ability of the keyboard, it seemsintuitive that if the keyboard surface itself could be a flat, or nearlyflat planar surface, then wiping the keyboard to clean it would be mucheasier. This means, however, that an alternative to the physicalmechanical or membrane keys of the keyboard would need to be found.

Therefore, there is a need to improve on the above methods for keyboardentry in a way which is easy to clean, allows the user to feel the keys,allows the user to rest their fingers on the keys, requires the same orless force to press a key as on a standard keyboard, is responsive tohuman touch, and allows the user to type as fast or faster as on astandard keyboard.

SUMMARY OF THE INVENTION

The method of the present invention is distinguished by the fact thatboth touch-capacitive and vibration sensors are used in conjunction onewith another. This approach makes it possible for the user to rest theirfingers on the keys, allowing them to type as they would on a regularkeyboard. As the user places their fingers on the keys, the touchcapacitive sensors (one per key) report the signal strength level ofeach key touched to the processor, but no keystroke is issued by thesystem until a corresponding “tap” (ie. vibration) is detected. When atap is detected, the present invention references the status of thetouch capacitance sensors before, during, and immediately after themoment in time the tap occurred. A key is determined to be asserted whenaround the moment of a tap, its touch sensor either cycles from on, thenoff, then on again (a key on which the user was resting their finger) orfrom off then on (a key on which the user was not resting their finger).The present invention is also able to detect the difference between anintentional key press and when a user has slid their finger from one keyto the next (as opposed to an actual key tap). For example, the user'smiddle finger may slide from one row to the next as the user reaches fora key and taps on it with their index finger. The present invention canthus distinguish between accidental and intentional key actuations.

There may be instances when a user needs to press a key on which theirfinger is already resting. They may do so in one of two ways: first,they may lift their finger and then tap it back down on the same key onwhich it was resting as they would any other key. Alternatively, theuser may press down harder on the key without lifting their fingercompletely off the key, in which case the touch sensor for that keyemits a stronger signal than when the finger was resting on the key morelightly. The stronger signal is detected and a key press is asserted.

The method of the present invention has a number of very significantadvantages over prior flat keyboard systems such as those disclosed byChien and Arnon. One is that the keyboard can have tactile key surfacesso the user can maintain the position of their hands on the keyboard(and thus by able to type without looking at their hands). In apreferred embodiment, the tactile surface is accomplished by shallowindentations, or key “wells”, over each key. The key wells are graduallysloped in a way that is still easy to wipe clean, yet deep enough tofeel with the finger. In another preferred embodiment, there are smallprotrusions on the “home” keys (f and j keys) typically touched by thepointer finger. In yet another preferred embodiment, the key wells areslightly deeper on the home keys as well as the keys typically rested-onby the little fingers (“a” and “;” keys). This allows the user strongeranchor points on the keys normally used to anchor the position of theirhands to the keyboard.

In contrast to the vibration-only system described by Chien orZiemkowski, the present invention allows simultaneous key pressesbetween two or more keys by using the touch-capacitive sensors on eachkey without requiring an additional mode of sensors (such as pressure).In a similar manner, key repeats are also honored when caused by a userholding down a key for an extended period of time.

The method of the present invention has significant advantages overprior capacitive keyboards such as that disclosed by Danish. One suchadvantage is that the user can rest their fingers on the keys withoutcausing a key actuation to occur. Another is that the user can type bytouch without having to look at the keyboard.

The system of the present invention allows the user to view a virtualimage of the keys through a transparent top planar surface. In apreferred embodiment, the virtual image is printed on a flat label thatis located under a transparent top planar surface that may (or may not)have key wells.

The system of the present invention can accommodate a wirelessbattery-powered implementation. A number of innovations are used toconserve battery life. One innovation is the entire system can be put inlow-power mode (or “sleep” mode) with the exception of a proximitysensor (or sensors) that can detect when a user's hand approaches thekeyboard. Upon detecting the presence of said user's hands, theproximity sensor “wakes up” the rest of the system. In this way, thesystem remains in low power mode while it is not being used. A furtherpower-conservation innovation is achieved by putting thetouch-capacitance sensors in lower-power mode and then periodicallywaking them up to quickly sample the state of each key. The duty cycleof this approach is such that the touch-sensors are in sleep mode mostof the time—even when the keyboard is being used, thus extending thelife of the system's batteries.

Because the system of the present invention can be wireless, it iscommon for it to be moved while the device is operational. This mayresult in unintentional key assertions. To alleviate this problem, thevibration sensor (also known as an accelerometer) can detect when thedevice is being moved, and temporarily suspend operation during thattime. Once the keyboard stops moving, operation can be automaticallyrestored.

The system of the present invention includes a speaker to provideaudible feedback when a user actuates a key. The sound may be a click,beep, digitized recording of an actual key click, or any other shortsound.

The method of the present invention allows for numerous user settingsthat can be adjusted from the keyboard itself. These include adjustmentsto the touch-capacitive sensitivity, the tap sensitivity, and the volumeof the audible feedback.

The method of the present invention also detects when a keyboard isbeing wiped. There is a two-key combination assigned to “pause” thekeyboard so it can be cleaned. However, some users forget to do this andjust begin wiping down the keyboard to clean it, without first pausingits operation. This can result in unintended keystrokes. Accordingly,the present invention detects when a wipe motion is taking place andautomatically pauses the keyboard's operation for the user. Anykeystrokes that were asserted immediately prior to the detection of awipe and which are subsequently deemed to have been part of the wipingmotion may be reversed automatically by the system issuing a backspaceor delete key for each unintentional key assertion. The keyboard pauselight flashes, reminding the user to re-enable the keyboard operationwith the two-key combination once they are done cleaning it.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred and alternative examples of the present invention aredescribed in detail below with reference to the following drawings:

FIG. 1 is a hardware block diagram showing the typical hardwarecomponents of a system which embodies the present invention as shown inFIG. 2;

FIG. 2 is a schematic view of an embodiment of a flat-surfaced keyboardof the present invention;

FIG. 3 is cross-section view of an embodiment of a flat-surfacedkeyboard of the present invention showing the layers of the assembly;

FIGS. 4A through 4I show an embodiment of a software algorithm toimplement the method of the present invention in order to detect validkey presses and a wiping gesture; and

FIGS. 5A through 5E show an embodiment of a software algorithm toimplement the method of the present invention in order to detectcontamination and clean conditions of the surface of the device.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 shows a simplified block diagram of the hardware components of anembodiment of the Touch/Tap Sensitive Cleanable Keyboard 100. The device100 includes a flat planar surface that houses a proximity sensor(s)120, capacitive touch sensors 130, a vibration sensor(s) 140, an audiospeaker 150, and LED visual indicators 160. The sensor components 120,130, & 140 provide input to the CPU (processor) 110 notifying it ofcontact events when the keyboard surface is approached or touched by theuser's hands, typically mediated by a hardware controller thatinterprets the raw signals received from the sensors and communicatesthe information to the CPU 110 using a known communication protocol viaan available data port. Similarly, the CPU 110 communicates with ahardware controller for turning on LED indicators and outputtingappropriate auditory signals to the speaker. The processor 110 hasaccess to a memory 170, which may include a combination of temporaryand/or permanent storage, and both read-only and writable memory (randomaccess memory or RAM), read-only memory (ROM), writable non-volatilememory such as FLASH memory, hard drives, and so forth. The memory 170includes program memory 180 that contains all the programs and softwaresuch as an operating system 181, the Touch-Tap Detection software 182,and any other application programs 183. The memory 170 also includesdata memory 190 that includes the data array of the touch capacitivesensor status for each key, storage for maintaining a record of useroptions and preferences 192, and any other data 193 required by anyelement of the device 100. The device 100 communicates functionscorresponding to user input to the host computer terminal 194 using aknown communication protocol via an available data connection (wired orwireless).

In order to maximize battery life and conserve power, it is importantthat the device 100 have a low power mode of operation when it is notbeing used. In a typical use scenario, as a user brings their hand(s)into contact with the device, the proximity sensor 120 detects this andsends a signal to wake-up the CPU 110 (which may or may not have been inlow-power, or “sleep” mode), which in turn wakes up the rest of thesystem 100.

As the user's fingers come into contact with the flat planar surface,capacitive touch sensors 130 are asserted. Periodically, the CPU 110samples the status of each touch sensor and stores the result in datamemory 191. Under the support of operating system software 181, the CPUascertains the location of each touch sensor that is asserted and mapsits location to a function (typically a keyboard key). Independently,the CPU 110 and touch/tap detection software 182 monitor the status ofthe vibration sensor 140. When a user taps on the planar surface,typically to type a key, a corresponding vibration is emitted throughoutthe system that is detected by the vibration sensor 140. When a validtap is detected, the CPU 110, supported by software 182, performs analgorithmic analysis of the sensor data contained in memory 191 todetermine which area of the planar surface was tapped on. If a validtap-touch is determined by the algorithm (see FIG. 4A-H), the mappedfunction for that location is sent to the host computer terminal 194.

In an embodiment, the vibration sensor is also an accelerometer that candetect motion. This is used to detect when the device is being moved,allowing the option to have the device's operation temporarily suspendeduntil it stops moving. The scheme helps to avoid unintended keystrokesfrom occurring while the keyboard is being moved, and also makes itpossible for the user to touch anywhere on the surface of the keyboardas they are moving it.

FIG. 2 shows a schematic view representative of a typical host computerterminal 205 and the present invention 200. A flat, or nearly flatsurface 200 is present to the user on which the user makes selectionswith their hands or fingers. In an embodiment, the planar surface 200presents an image of keyboard keys 210, 230, 240 and so on, as well as amouse-pointer touch pad 260 with corresponding left 280 and right 270mouse buttons. A special function key 290 is provided as a means to setuser preferences on the keyboard when it is pressed simultaneously withother keys. For example, the function key 290 is pressed simultaneouslywith the pause key 240 to temporarily suspend operation of the keyboard(typically so it can be cleaned). Other LED indicators on specific keysprovide the user with feedback to indicate caps lock, numlock, a pausedstate.

In yet another embodiment, other users settings may be set directly onthe keyboard. A separate row of LEDs 215 are used to indicate a genericlevel of 0 through 5. To enter Settings Mode, the user simultaneouslypresses the function key 290 with one of a plurality of other keys 235to indicate the setting they wish to poll or change. An LED indicatorlights above the selected setting key 235 while at the same time, thecurrent level of the setting is indicated on the generic level LEDs, 0through 5. The user can then change the level of the setting by pressingthe desired key below the generic level LEDs. To exit Settings Mode, theuser once again simultaneously pressed the function key and the settingkey, or waits a for a pre-determined amount of time after which thesystem automatically exits to normal mode. In the embodiment, the usermade poll and set the following settings: volume, touch sensitivity, tapsensitivity, the cleaning level, the strength of the wireless signal,the strength of the battery, and the sensitivity of the proximitysensor.

In yet another embodiment, the top planar surface of the device hasshallow impressions, or “key wells” to provide a tactile feel indicatingthe location of a key. The key wells are deep enough to allow a humanfinger to feel them, but shallow enough to still allow easy wiping andcleaning of the surface. The two keys commonly referred to as the homekeys (typically the “f” and “j” keys on an English keyboard) 230 mayhave additional tactile markers on them, such as a small protrusion ascommonly found on standard keyboards. In yet another embodiment, the keywells are slightly deeper on the home keys 230 as well as the keystypically rested-on by the little fingers 210 (“a” and “;” keys). Thisallows the user stronger anchor points on the keys where studies haveshown the user typically rests their fingers.

FIG. 3 shows a cross-section of the components making up the top layerof the embodiment of the present invention. A top transparent planarlayer 300 is the outer-most layer that the user touches. Shallowindentations, or key wells 340, are located over each key. An image 310of the keyboard keys is presented on the underside of the top planarsurface 300 by printing, painting, engraving, or affixing a label. Aprinted circuit-board 320 is adhered to the underside of the planarsurface 300 that has conductive traces 330 that make up the touchsensors. Other electronic components, such as LEDs and the vibrationsensor(s) 350 are located on the underside of the printed circuit-board320.

FIGS. 4A through 4I show a process flow chart of an embodiment ofsoftware 182 to implement the Cleanable Touch & Tap Sensitive Keyboard.FIG. 4A shows a flow chart of an embodiment of the Main ProcessingRoutine 4100 of the Cleanable Touch & Tap sensitive Keyboard software182. At block 4105, when the process is first started, various systemvariables are initialized including the digital status of the touchsensors (Q) and the analog level of the touch sensors (A). At block4110, the process waits for a pre-determined polling period thencaptures the values of all the touch capacitive sensors in block 4115. AKey Release Detection routine of FIG. 4B is invoked at block 4120 todetermine if a key that was previously asserted has been released. A KeyPress Detection routine of FIG. 4C is invoked at block 4125 to determineif a key that was previously released has been asserted. A WipeDetection routine of FIG. 4F is invoked at block 4130 to determine if awipe motion has been detected on the keyboard and if so, toautomatically suspend operation of the keyboard. The Wipe Detectionroutine can also be used to determine if the keyboard has beenadequately cleaned.

FIG. 4B shows a flow chart of an embodiment of the Key Release Detectionroutine 4200. At block 4205 each key sensor status that is stored forthe current sample (N) is acquired and compared with the status of thesame key from the previous sample (N−1) in block 4210. If the key wasasserted (ie. value=1) in the previous sample, but is unasserted in thecurrent sample (ie. value=0) then the key is determined to have justgone through a valid key release state in block 4215. All keys are thusevaluated in block 4220 and then the routine returns in block 4225.

FIG. 4C shows a flow chart of an embodiment of the Key Press Detectionroutine 4300. This routine begins by determining if a valid tap hasoccurred in block 4305 as determined by the vibration sensor(s) 140. Ifno tap is detected, the routine goes on to the press detection routinein FIG. 4I in block 4310. If a valid tap is detected, the process beginsby clearing the two data containers for Candidate Keys (ie. keys whichhave changed their state from unasserted to asserted) and Valid Keys(ie. keys which have been determined to be tapped on). Because the tapsensor and touch sensor may not be asserted at precisely the same momentin time, the comparison of the state of each key is bracketed by thecurrent sample as well as the past two (or more) samples in block 4320and block 4325. In block 4330, the routine determines if the current keybeing examined has changed from unasserted to asserted, and if so, it ismarked as a Candidate Key in block 4335. The process continues in block4340 until all keys have been examined. If there are no Candidate Keysidentified, the process continues to FIG. 4D in block 4350. If there areCandidate Keys, the process continues in block 4355 until all keys inthe queue have been examined and then the routine returns in block 4360.

FIG. 4D shows a flow chart of an embodiment of the continuation of theKey Press Detection routine of FIG. 4C in block 4400. At this point ofthe routine, at least one (or more) keys have been identified asCandidate Keys (ie. the key's touch sensor status has changed fromunasserted to asserted). A common problem with touch capacitivekeyboards is “phantom” key strokes that are the result of the usersliding their fingers from one row to an adjacent row when they aretyping with another finger. When an accidental slide occurs, there istypically a moment in time when both adjacent keys are asserted at thesame time as the finger slides between the two keys. The routineexamines each candidate key in block 4405 and compares its status withkeys that are adjacent to it on a different row in block 4410. In block4415, if the adjacent key is asserted at the same time as the currentsample of the asserted Candidate key, or if the adjacent key wasasserted immediately prior to the current sample of the assertedCandidate key then the circumstance is deemed to be the result of afinger slide and the Candidate key is ignored. Block 4416 shows a tableof a sample data set where a key slide has been determined due to theCandidate Key and the Adjacent Row Key being asserted at the same momentin time. In the table, it can be seen that while the candidate'sasserted state went from a 0 to a 1 (qualifying it as a Candidate Key),an adjacent row key transitioned from asserted to unasserted, with atleast one sample set n−1 where both the Candidate Key and Adjacent RowKey were asserted at the same time. Block 4417 shows a table of a sampledata set where a key slide has been determined due to the Adjacent RowKey being asserted immediately before the moment in time when theCandidate Key was asserted. Since it is very unnatural and difficult toplace a second finger on an adjacent row key at the same time the firstfinger is on a candidate key, it is assumed that the circumstance foundto be true in 4415 most likely occurred as the result of the usersliding the same finger from one key to a key on an adjacent row. Sincethe premise of the Touch-Tap Cleanable Keyboard is that in order for akey to be valid, it must be tapped on or pressed (not just slid to), thecircumstance found to be true in 4415 is ruled out as a Valid Key Press.This process continues for each adjacent-row key in block 4420. If theCandidate Key was found not to have occurred as the result of a slidemotion, then it is added to the set of Valid Keys in block 4425. Thisprocess continues for each Candidate Key in block 4430. Once the slideanalysis has been performed on each Candidate Key, the process moves onto the flowchart shown in FIG. 4E.

FIG. 4E shows a flow chart of an embodiment of the continuation of theKey Press Detection routine of FIG. 4D in block 4500. Block 4505examines the total number of Valid Keys and determines if the numberexceed an acceptable threshold. If so, the key presses are ignored. Forexample, a user could slap their entire open hand down on the keyboardwhich would result in multiple Valid Keys, even though the user wasclearly not typing. If that is the case, the routine returns in block4515. Otherwise, the routine determines a Valid Key was pressed andsends the command to the host computer terminal 194 in block 4520. Theprocess continues for each Valid Key in block 4525 and then returns inblock 4530.

FIG. 4F shows a flow chart of an embodiment of the Wipe Detectionroutine 4600. It is common for a user to forget to disable (or “pause”)the keyboard's operation prior to cleaning it. It is therefore desirableto detect when a wiping motion occurs on the surface of the keyboard andautomatically disable it for the user to avoid accidental keystrokesfrom being issued to the Host Computer Terminal 194. A Sensor FootprintDetection routine of FIGURE H is invoked in block 4605 to determine thesize of the current “footprint” of the sensors. (The term “footprint” isused to describe a group of adjacent key sensors that are asserted atthe same time). Block 4610 clears all footprint records' update flags inpreparation for the analysis that will detect only newly-formedfootprints or previous footprints that have moved. Blocks 4615, 4620,and 4625 retrieves each detected footprint and each existing footprintand compares their size and location. If the footprints are similar insize and location, Block 4630 determines the size change and movementvector between them, updates F in block 4635 and sets its Updated flagto true in 4650. If the DF and F footprints are not similar in size, theprocess continues to examine other footprint records in block 4640. Onceall footprints have been compared, the process creates a new footprintrecord in 4645 and sets its Updated flag to true. The process continuesfor other detect footprints in block 4655. Once all detected footprintshave been processed, all footprint records whose Updated flag is falseare removed in block 4660 and the process continues in block 4665 to theflowchart shown in FIG. 4G, passing along newly-formed footprints andpre-existing footprints that have moved.

FIG. 4G shows a flow chart of an embodiment of the continuation of theWipe Detection routine from FIG. 4F in block 4700. Each footprint record(F) is examined in block 4705. Block 4710 determines if there are enoughfootprint records to proceed with the wipe detection routine. If so,block 4715 determines if the of movement of the footprints are in thesame direction and if the size of the footprints are relativelyconstant. If so, a valid wipe is declared in block 4720 and the processterminates in block 4725. If the analyzed footprints do not qualify as awipe, the routine continues to examine all remaining footprints in block4730 and then returns in block 4735.

FIG. 4H shows a flow chart of an embodiment of the Sensor FootprintDetection routine 4800. The purpose of this routine is to find areaswhere a number of adjacent touch sensors are simultaneously asserted(ie. “footprints”). The routine begins by examining each key sensor inthe Touch Capacitive Sensor History Array 191 in block 4805. Each key(k) is processed in block 4810 and checked to see if it is presentlyasserted in block 4815. If it is, a new potential footprint is createdin block 4820. Block 4825 examines each key (j) that is adjacent to key(k) and checks if it is asserted in block 4830. If the adjacent key (j)is asserted then block 4835 checks to see if it is already included inthe potential footprint. If not, block 4840 adds the adjacent key (j) tokey (k)'s potential footprint. Block 4845 ensures that both key(k) andadjacent key(j) are referenced to each other. Block 4850 marks theadjacent key(j) as processed. The process continues in block 4855 untilall potential adjacent keys have been examined, after which block 4860marks the key(k) as processed. The entire process repeats in block 4865until all keys have been examined.

FIG. 4I shows a flow chart of an embodiment of the Press-after-RestDetection routine. The process starts by clearing the set of Valid Keys(V) in block 4810. Block 4820 examines each entry in the queue (e) fromthe present sample (N) down to a determined previous sample (shown inthis example as N−2). Block 4830 retrieves the analog signal value (A)for the touch sensor for each key (ke). Block 4840 determines if theanalog signal value ke is above the Rest Threshold (ie. the sensorreading for a typical resting finger). If the analog signal value ke isnot above the Rest Threshold, the process skips to block 4870 where thenext key is processed. If the analog signal value ke is above the RestThreshold, block 4850 determines if the change in the analog signalvalue between ke and the previous sample ke−1 exceeds the PressThreshold (shown as SLOPE(ke, ke−1)). Block 4850 also determines if thechange immediately prior to ke−1 was a slight lift, followed by a press(to account for the instance when a user may lift their finger slightlyon a key without completely taking it off the key, just prior toasserting a press motion). If either of these conditions exist, theprocess adds ke to the set of Valid Keys (V) in block 4860. If either ofthese conditions do not exist, the process continues by examining thenext keys A(e) in block 4870. Once all keys are considered in block4880, the process exits back to the flowchart shown in FIG. 4E, in block4890.

There are a number of optionally advantageous aspects of the keyboard asdisclosed herein. An example set of optionally advantageous aspects areitemized below: the use of hardened acrylic, glass, annealed glass, orother scratch-resistant transparent material for the top surface; theuse of anti-microbial solid surface material as the base of theenclosure; the use of aluminum (formed, machined, etc) as the base ofthe enclosure; the method of adhering the transparent top surface to thebase; sealing the enclosure against intrusion of liquid or dust to theinterior of the enclosure; the use of iridium tin oxide (ITO) to provideconductive transparent traces for the touch sensor; and/or though theuse of ITO technology, the ability to make the keyboard completelytransparent by etching or otherwise affixing the key images to theunderside of the glass, as well as the ITO traces; and the use of areplaceable snap-on transparent cover for the top surface.

The keyboard is ideally suited to easy cleaning and disinfection. Asdescribed above, the operation of the keyboard can be temporarilysuspended, either by a key combination or a wipe detection, and thensanitized or disinfected. In another aspect, the system is able todetermine when it is likely that the touch surface has becomecontaminated to the point that it should be cleaned. It does this bykeeping track of the cumulative activity that has taken place on thetouch surface since the last cleaning. The activity level is determinedby a combination of one or more of the following factors: the number oftouches on the surface (using the touch sensors 130), the number ofslides over the surface (using the touch sensors 130), the number oftaps on the surface (using the vibration sensor 140), the amount ofmovement of the keyboard (using the vibration sensor 140), and thenumber of times the proximity sensor has been activated (using theproximity sensor 120). When the activity level reaches a user-settablethreshold, then a contamination alert is activated (which may be alight, a series of lights, an audible sound, or an electronicnotification to the host computer terminal).

In an embodiment, host computer terminals are part of a computernetwork, over which an administrator could monitor the contaminationstatus of each keyboard connected to the host computer terminals. Forexample, a hospital infection control steward could be notified if anykeyboards are beyond the contamination threshold and could take steps toquickly have those devices disinfected, thereby maintaining theintegrity of the infection controlled environment.

In another aspect, the system is able to determine when the touchsurface has been wiped sufficiently enough to clear the contaminationalert. When a wiping action takes place, a “footprint”, or multipleactivated adjacent touch sensors, traverses across the plane of thesurface/keyboard. The path of the footprint is observed by the systemthereby making it possible to detect whether or not the wiping activitytook place over the entire surface of the keyboard, and also how manywipes back and forth took place. Once the wiping activity reaches auser-definable threshold, the contamination alert is deactivated, asexplained in FIGS. 5A through 5E below.

FIGS. 5A through 5E show a process flow chart of an embodiment ofsoftware 182 to implement a contamination and clean detection process.FIG. 5A shows a flow chart of an embodiment of the Main ProcessingRoutine 5100 of the Contamination and Clean Detection routines of theCleanable Touch & Tap sensitive Keyboard software 182. Block 5110initializes an “Activity Level” variable AL. This variable is used totrack the amount of activity on the surface of the keyboard that maycontribute to its contamination. Block 5120 checks to see if theContamination Threshold has been exceeded (see FIG. 5B). If thethreshold isn't exceeded, the routine continues in a loop until theContamination Threshold is exceeded, upon which it activates theContamination Alert in block 5130. Block 5140 determines if the keyboarduser setting is set to use the clean wipe detection routine. If not, theprocess waits for a keyboard pause and unpause in block 5150 and thenclears the Contamination Alert. If the keyboard user setting is set touse the clean wipe detection routine, then the process waits at block5160 until the Clean Threshold has been exceeded (see FIG. 5C). Once theClean Threshold has been reached, the process clears the ContaminationAlert in block 5170 and then loops back to begin the process again fromthe start at block 5110.

FIG. 5B shows a flowchart of an embodiment of the ContaminationDetection routine 5200 of the Cleanable Touch & Tap Sensitive Keyboard.Block 5205 examines each touch sensor and determines if it is assertedin 5210. If it is asserted, the Activity Level counter is incremented inblock 5220 and loops back to check other keys in block 5230. Block 5235determines if the device is being moved (via the vibration sensor, alsoknown as an accelerometer). If so, the Activity Level counter isincremented in block 5250. Block 5255 determines if the user's handshave approached the keyboard (via the proximity sensor 120). If so, theActivity Level counter is incremented in block 5260. A weighted sum ofall activity triggers is calculated in block 5265 to determine theContamination Level for the given time slice n.

FIG. 5C shows a flowchart of an embodiment of the Clean Detectionroutine 5300 of the Cleanable Touch & Tap Sensitive Surface device.Block 5305 determines what, if any, sensor “footprints” exist (see FIG.5E). The remainder of the flowchart in this figure determines if theidentified footprint is a valid moving footprint, the same as describedfor FIG. 4F (refer to the description for FIG. 4F above). The processthen continues on to FIG. 5D via block 5365.

FIG. 5D shows a flowchart of an embodiment of the continuation of theClean Detection routine 5400 of the Cleanable Touch & Tap SensitiveSurface device. Block 5405 examines each footprint record (F) determinedfrom analysis in FIG. 5C. Block 5410 determines if the footprint is ator near the edge of the touch surface. If not, the process continueslooking at other footprints. Block 5415 ensures that all sensors makingup the footprint moved in the same general direction and the size of thefootprint remained generally consistent. If not, then it is determinedto not be a valid moving footprint and “F” is removed from the candidatefootprints in block 5420. Otherwise, the Clean Level counter isincremented in block 5425 (since a wipe has traversed to the edge of thetouch surface). This continues for all footprint records in block 5430and then returns in block 5435. A user setting stored in memory 192determines the Clean Level Threshold. Once the Clean Level Threshold hasbeen exceeded, the Contamination Alert is cleared and the surfaced isdeemed to have been adequately cleaned.

In another aspect, the system is able to determine when the touchsurface has been wiped sufficiently enough to clear the contaminationalert. When a wiping action takes place, a “footprint”, or multipleactivated adjacent touch sensors, traverses across the plane of thekeyboard. The path of the footprint is observed by the system therebymaking it possible to detect whether or not the wiping activity tookplace over the entire surface of the keyboard, and also how many wipesback and forth took place. Once the wiping activity reaches auser-definable threshold, the contamination alert is deactivated.

In another aspect, the keyboard may be placed in a sterilization device(commonly referred to as an “autoclave”).

In another aspect, a dynamic display (such as an LCD or “electronic ink”display) can be placed below the top planar surface such that thefunctional assignment for each key as well as the associated visualdisplay can be changed dynamically, which is referred to as “softkeys”hereafter.

In another aspect, the dynamic key assignment may be determined manuallyby the user, or automatically by the system according to contextualchanges on the host computer. For example, one set of softkeys may bedisplayed for the current application, but then automatically changewhen a new application becomes active. Individual keys may also changewithin an application itself, depending on the workflow being followed.The implementation of this feature may take advantage of certain toolsoffered by the operating system on the Host Computing Terminal (eg.Widgets and Sideshow provided in the Windows operating system).

It is desirable to provide the user with some sort of haptic feedback tothe touching and actuation of a key. This may be accomplished in anumber of ways, which include but are not limited to “strikers,”strikers are interspersed throughout the keys that strike the glasssurface from beneath and give a tactile response to a key press. (i.e.the user would feel the sharp vibration of the striker hitting the glasswhenever they touched a key).

In another embodiment, the keyboard would vibrate when a key isactuated. (Similar to how a cell phone or pager vibrates).

In yet another embodiment, a tactile actuator is positioned between thetouch surface and the supporting base of the keyboard. When a key ispressed, the entire top surface depresses slightly against the tactileactuator, which produces a tactile response. (This is similar to thefeel and construction of a simple “clicking” switch).

Because the surface of the device is continuous, individual keys do nothave their own mechanical moving structure (as on traditionalkeyboards). Therefore, it may be possible for the user to miss tappingon the desired key by a small margin of error (between two keys, forexample). In such a case, the system would still detect a tap but thekey location of the tap would be ambiguous. To help improve accuracy,lexicon-based databases can be stored in the system, including databasesof common words, common letter-pairs, and common next-words. When anambiguous key activation occurs, the algorithm can disambiguate thechoice by referring to the databases to find the most likely letter ofall the candidate ambiguous letters. This disambiguation is done on aletter-by-letter basis without presenting any alternate choices to theuser via a display mechanism (which distinguishes it from prior art).

Because the surface is touch-sensitive and the user is permitted to resttheir fingers on the surface of the keys, it is difficult to determinethe difference between when the user intends for a key to be asserted asheld down and when they are simply resting their finger on the key aftertapping on it. This problem is solved by implementing a special gesturefor initializing a key repeat (or key press and hold). The user firsttaps on the desired key, quickly lifts their finger from the key, andthen taps again and holds their finger on the key in quick succession.From that point forward, as long as the user holds their finger on thekey, it is deemed to be asserted (or pressed). To end the key assertion,the user lifts their finger from the key.

In yet another embodiment, the contamination level of the touch surfacecan be determined using optical methods. For example, the transparenttop surface forms a light channel through which infrared or visiblelight is transmitted from one side to the other, where a photodiodedetects the level of light propagated. When contamination, such as oilyfingerprints, occurs on the outside of the touch surface, a certainamount of light escapes from the channel (employing Snell's law). In yetanother embodiment, lasers may be used to scan the touch surface todetect contamination.

While the focus of the embodiment described herein is for a keyboardapplication, someone skilled in the art will see that the system couldalso be successfully applied to any type of touch-screen device.

While the preferred embodiment of the invention has been illustrated anddescribed, as stated above, many changes can be made without departingfrom the spirit and scope of the invention. Accordingly, the scope ofthe invention is not limited by the disclosure of the preferredembodiment. Instead, the invention should be determined entirely byreference to the claims that follow.

1. A method of discerning user input on a solid planar touch-sensitivesurface, the method comprising: at a processor, recording two or moreconcurrent user touches of the solid planar touch-sensitive surfacebased on two or more signals generated by a plurality of touch sensorsincluded in the touch-sensitive surface; receiving vibration signalsfrom one or more vibration sensors coupled to the touch-sensitivesurface; and determining whether the vibration signals constitute a usertap event, based on pre-defined criteria; and correlating the two ormore concurrent user touches with the determined user tap event todisambiguate between the user resting on the touch surface and assertinga selection on the touch surface, thereby outputting an actionassociated with the asserted selection, wherein the touch sensors arephysically and operationally different than the vibration sensors. 2.The method of claim 1, wherein the solid planar touch-sensitive surfacecomprises a plurality of alphanumeric keys associated with correspondingtouch sensors.
 3. The method of claim 2, wherein the touch-sensitivesurface comprises first tactile markers identifying the location of eachkey.
 4. The method of claim 3, wherein the first tactile markers areshallow indentations on the touch-sensitive surface.
 5. The method ofclaim 3, wherein second tactile markers that are distinguished fromfirst tactile markers are placed on predesignated home keys.
 6. Themethod of claim 3, wherein second tactile markers that are distinguishedfrom first tactile markers are placed on outer-lying keys.
 7. The methodof claim 2, further comprising at a communication device communicatingwith a host computer by wired or wireless methods.
 8. The method ofclaim 2, further comprising generating a command signal after acombination of keys have been asserted.
 9. The method of claim 2,further comprising at the processor suspending operation of the surfaceby activating a disabling key combination of one of a single key, two ormore simultaneous key activations, or a series of two or more sequentialkey presses.
 10. The method of claim 2, wherein user settings arechangeable on the touch surface.
 11. The method of claim 10, wherein theuser settings are displayed on a plurality of LED indicators.
 12. Themethod of claim 2, further comprising: at the processor, receiving asecond tap event signal; and asserting a key press and hold event basedon the received second tap event signal and a recorded user touch on thesame key associated with the previous asserted selection.
 13. The methodof claim 1, further comprising at an output device emitting an audiblesound when a selection is asserted.
 14. The method of claim 1, furthercomprising at the processor determining when one of the touch sensorshas been touched according to a sliding motion.
 15. The method of claim14, wherein the asserted selection is associated with one of the touchsensors that was not recently determined to have been touched accordingto the sliding motion.
 16. The method of claim 1, further comprising: atthe processor, detecting a wiping motion based on the recorded usertouches; and suspending assertions when a wiping motion has beendetected.
 17. The method of claim 16, further comprising removing one ormore selections asserted before detection of the wipe motion.
 18. Themethod of claim 1, wherein the surface performs the function of a mousepointing device.
 19. The method of claim 1, wherein the surface is atouch-screen on a dynamic display computing device.
 20. The method ofclaim 1, wherein the surface comprises a numeric keypad.
 21. The methodof claim 1, wherein the surface is user definable.
 22. The method ofclaim 1, wherein sensitivity of the touch sensors is adjustable.
 23. Themethod of claim 1, wherein the sensitivity of the vibration sensors isadjustable.
 24. The method of claim 1, further comprising: at aproximity sensor generating a sensing signal when an object comes withina threshold distance; at the processor, sensing when the user is aboutto use the surface based on the sensing signal; and changing from a lowpower consumption state of the surface to a full power operation statewhen it is sensed the user is about to use the surface.
 25. The methodof claim 1, further comprising: at the processor, determining a numberof recorded user touches since a predefined condition; and enabling awarning indicator if the determined number of recorded user touchesexceeds a threshold.
 26. The method of claim 1, further comprising atthe processor cumulatively recording a level of user interaction withthe touch surface until a first contamination threshold is reached. 27.The method of claim 26, further comprising at the processor asserting analert when the first contamination threshold is reached.
 28. The methodof claim 27, wherein the alert is at least one of a warning light, anaudible sound, a vibration, or a command sent to a host computerterminal.
 29. The method of claim 27, wherein cumulatively recording iscontinued until a first user cleaning threshold is exceeded.
 30. Themethod of claim 29, wherein the first user cleaning threshold is basedon a number of wipes and touch surface area wiped.
 31. The method ofclaim 29, further comprising at the processor unasserting the alert whenthe cleaning level threshold is exceeded.
 32. The method of claim 27,wherein the first user cleaning threshold is based on an array of thetouch sensors.
 33. The method of claim 27, wherein the level of userinteraction comprises one or more of recorded user touches, received tapevents, sensed movements of the surface or determinations when the useris in close proximity of the device.
 34. The method of claim 1, whereina key is asserted to be held down by tapping the surface at the locationof the key, lifting and then tapping and holding again in quicksuccession.
 35. The method of claim 34, wherein a key that is assertedto be held down is released by lifting off the key.
 36. The method ofclaim 1, further comprising: at the processor, receiving a signalassociated with a sensed movement of the touch surface; and suspendingoperation of the surface if the sensed movement is above a predefinedthreshold.
 37. A system comprising: a means for recording two or moreconcurrent user touches of the solid planar touch-sensitive surfacebased on two or more signals generated by a plurality of touch sensorsincluded in the touch-sensitive surface; a means for receiving vibrationsignals from one or more vibration sensors coupled to thetouch-sensitive surface; and a means for determining whether thevibration signals constitute a user tap event, based on pre-definedcriteria; and a means for correlating the two or more concurrent usertouches with the determined user tap event to disambiguate between theuser resting on the touch surface and asserting a selection on the touchsurface, thereby outputting an action associated with the assertedselection, wherein the touch sensors are physically and operationallydifferent than the vibration sensors.